The objective is to develop a reliable sensitive method for quantification of acetaldehyde (AcH) in breath originating from ethanol (EtOH) metabolism. The technique is based on chemically trapping AcH from breath as a sodium bisulfite addition product allowing storage and transport of samples. AcH released into a headspace is analyzed by gas chromatography. Evaluation of this proposed technique will include statistical analysis of the results from clinical samples for precision and reliability.